<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>ES常量</title>
</head>
<body>
<script>
    const PI =3.1415926;//定义常量必须赋值
    //PI=3.14;  常量不允许修改

    console.log(PI);
</script>
</body>
</html>